Driverless cars for driverless humans?

August 2014

Google recently announced a plan to deploy 100 driverless cars around their campus. In certain States, driverless cars are permitted provided there is the opportunity for human intervention. It probably says something about the way my mind works (and that I have little or no control over it) that I am linking Google’s news with ongoing developments in the fields of neuroscience and physiology.

On several occasions in this newsletter, and in several chapters of my upcoming book, Dance with the Elephants, I have pointed out that we humans are less in control of our thoughts, emotions and physical movements than we think. The Princeton cognitive psychologist, George A. Miller, published an important work entitled “The Magical Number Seven, Plus or Minus Two: Some Limits on Our Capacity for Processing Information”. He argued that our short-term memory can only process between five and nine pieces of information to which it has been exposed only briefly. He identified that these pieces of information were chunks as opposed to single bits of data; for a native language speaker one word will represent one bit, but for a non-speaker that word could consist of 3 or 4 phonetic bits.

The brain is an information processing and messaging centre, and the nervous system is a channel for the processing of information. Researchers expected to find that the brain would show a tremendous capability for processing large quantities of information. But when they studied the brain during ‘intelligent’ activities such as playing music or reading, they found a capability of around 50 bits per second. For example, a typical reading rate of 300 words per minute equates to about 5 words per second. An average of 5 characters per word, with roughly 2 bits per character gives us the rate of 50 bits per second. The actual rate will vary depending on the complexity of the language, but contrast 50 bits with the fact that our senses gather some 11 million bits per second from our environment.

When I talk about our brains processing some 11 million bits per second, I often encounter somewhat sceptical reactions. People cannot (consciously) take in such vastness, it seems. Our senses process the following volumes of data (in bits per second):-

Sight 10,000,000

Touch 1,000,000

Sound 100,000

Smell 100,000

Taste 1,000

It is evident that visual images represent the majority of the information traffic. Everyday vision involves an astonishing range of abilities. We see colours, identify movements and shapes, judge distance and speed, and estimate the size of distant objects. Even though images fall on the retina in two dimensions, we manage to see images in 3-D. We fill in blind spots, automatically correct distorted information, and automatically delete extraneous images that cloud our view (such as our noses, the blood vessels in our eyes).

The equipment that achieves these tasks is by far the most powerful and complex of the sensory systems. The retina, which contains 150 million light-sensitive rod and cone cells, is actually an outgrowth of the brain. In the brain itself, there are hundreds of millions of neurons devoted to visual processing, taking up about 30% of the cortex, as compared to 8% for touch and just 3% for hearing. Each of the two optic nerves, which carry signals from the retina to the brain, consists of a million fibres. In contrast, each auditory nerve carries a mere 30,000.

So a lot of our brain is devoted to visual processing. There is a parallel that helps to make sense of this pre-eminence of visual images. When you think about the explosion of data that is associated with storing or transmitting visual images (on hard disk drives or over the internet) think about how much your data storage needs have grown and how much of the growth is caused by images.

If our senses send 11 million bits per second to our brain, but our conscious mind only copes with 50 bits per second, what’s going on?

Firstly, a tremendous amount of compression takes place if we are reducing 11 million to 50. This is partly enabled by a half-second delay between the instant our senses receive a stimulus and the moment the mind is conscious of the sensation. To cope with this delay, the body has a reflex system that responds in less than one-tenth of a second, before the mind is conscious of the stimulus.

Secondly, there is the tremendous processing power of the brain. With 100 billion cells, each with connections to thousands of other brain cells, the brain may be capable of performing as many as 100 billion operations per second.

We assume that our conscience brains are dominant. This is far from true; the vast proportion of the processing occurs in the ‘other than conscious’ brain. Practised and habitual processing are important because they train the brain to carry out activities ‘automatically’, without conscious intervention. That is why ‘simple’ tasks, such as walking, eating, or monitoring a driverless car, are best done without interference from our consciousness, which doesn’t have sufficient processing capability to cope with the demands of these tasks.

Driverless cars are legal where there is the possibility of human intervention. Just don’t assume that such interventions will be conscious. Are the law-makers consciously aware of what they have enacted? Or are the laws based on interventions coming from our ‘other than conscious’ minds? I think they better be, in both cases.